In the field of cardiac imaging using magnetic resonance there has recently been great interest in the study of myocardial perfusion. Perfusion deficits revealed by such studies indicate areas of actual or potential damage to heart muscle, for example as a result of coronary infarction or total or partial arterial occlusion, and the technique can be used to monitor and assess the success of pharmacological or surgical attempts to reperfuse areas of perfusion deficit.
To date the major thrust has been in the development of first-pass myocardial perfusion imaging using T1-weighted sequences and low molecular weight gadolinium chelate MR contrast agents, such as gadodiamide (Omniscan7, Nycomed Amersham) and gadopentetate (Magnevist7, Schering), agents which distribute throughout the extracellular space, i.e. within both the blood vessels and the interstitium. Generally the MR image acquisition sequences used have been very fast gradient-echo sequences or multishot echo planar imaging (EPI) sequences which rely on fast read out and a short TR in order to achieve sufficient resolution and acquire images of multiple slices through the heart in each heart beat. Such sequences usually acquire 3 or 4 slices each heart beat or 6 to 8 interleaved slices in two heart beats and the in-plane resolution is generally about 2 to 3 mm.